1. Field of the Invention
The present invention relates generally to the field of wireless communications. More specifically, the present invention relates to a wireless device for allocating radio spectrum access in a wireless communication system.
2. Background Art
The configuration of wireless communications systems, and the allocation of radio spectrum access to wireless devices within these communications systems, has traditionally followed one of two extreme paths. In pre-planned wireless networks, the system designer typically assumes complete control over the operation of wireless devices that use a specified set of radio spectrum access parameters across a particular coverage area. Unlicensed systems have historically taken the opposite approach when configuring their access to radio spectrum resources. These systems assume a minimal knowledge of and no control over other types of wireless devices operating within a particular geographic area.
However, the radio spectrum access in mobile, ad hoc wireless networks is not easily configurable using the conventional means applied to either pre-planned wireless networks or unlicensed wireless networks. The mobile nature of ad hoc wireless systems severely limits the applicability of the detailed planning tools and the site surveys that are used to configure pre-planned wireless networks. Thus, in general, ad hoc networks are configured to access radio spectrum using a single set of radio spectrum access parameters that may not accurately reflect existing network conditions. In fact, recent reports indicate that congestion in wireless “hot spots” results not from the scarcity of radio spectrum resources, but from an inefficient means of accessing those resources.
The configuration and operation of wireless local-area network (WLAN) mesh networks, or ad hoc networks, is described within the draft IEEE 802.11s specification developed by “Working Group 11” of the IEEE LAN/MAN Standards Committee (IEEE 802) (e.g., see “Proposal Summary: Wi-Mesh Alliance Proposal B:31”, as described at http://www.ieee802.org/11/DocFiles/05/11-05-0573-03-000s-wi-mesh-alliance-proposal-summary.ppt, hereafter known as the “draft specification” and incorporated herein by reference in its entirety). The draft specification addresses the pressing need for the intelligent allocation of radio spectrum access in ad hoc networks, and it details a proposed Distributed Resource Control Access (DRCA) protocol through which two wireless devices within an ad hoc network negotiate their future access to IEEE 802.11-compatible radio spectrum. FIG. 1 is an illustration of the proposed DRCA protocol between two wireless devices.
The DRCA protocol, as outlined in FIG. 1, requires that one node, the source mesh point (Source MP), submits a Mesh Transmit Opportunity (MTXOP) to a second node, the destination mesh point (Dest MP), across a designated radio channel. The MTXOP contains a range of radio spectrum access parameters acceptable at the source mesh point for data transfer to the destination mesh point. The destination mesh point, upon receipt of the MTXOP, must either agree to the proposed set of radio spectrum access parameters and select a specific set of access parameters from that proposed set, or reject the proposed set of radio spectrum access parameters and submit a counter-proposal to the source mesh point containing an additional set of radio spectrum access parameters.
In the first case, when the destination mesh point has responded with an operating configuration within the proposed range, the source must acknowledge that response to complete the DRCA protocol. In the second case, the source mesh point must select a set of operating parameters from within the counter-proposed range and send an acknowledgment to the destination mesh point, or it must reject the counterproposal and send a message acknowledging that rejection. The destination mesh point then acknowledges the decision of the source mesh point regarding the counter-proposed range of radio spectrum access parameters.
Although addressing the need to automatically configure the radio spectrum usage within an ad hoc wireless network, the draft specification is insufficient to meet the increasing demands on wireless bandwidth brought about by the interaction of ad hoc wireless networks with pre-planned and unlicensed wireless networks. Specifically, the draft specification fails to address the quality of a proposed range of radio spectrum access parameters. The DRCA protocol requires the source and destination nodes need only to exchange a binary indication as to whether a particular set of radio spectrum access parameters is “clear” and available for use. However, in order for ad hoc wireless networks to access radio spectrum resources in an optimum fashion, it is essential to characterize both the accessibility of radio spectrum resources and the quality of these accessible resources.
Further, the draft specification requires that the radio spectrum resources be quantified in terms of contiguous channels (i.e., the division of radio spectrum into frequency bands). This requirement is especially limiting when allocating radio spectrum access in wireless networks composed of non-conventional wireless devices such as “smart” radios. These emerging technologies are able to access radio spectrum resources non-contiguously in frequency, time, and geographic position.
The proposed DRCA protocol for negotiating radio spectrum access also fails to inform the participating devices as to why a particular negotiation fails. This failure prevents the proposed DRCA protocol from implementing adaptive algorithms that learn from pervious failed negotiations and improve future performance based on these previous failures.
A need thus exists for methods that facilitate the dynamic allocation of radio spectrum access to wireless devices operating within a wireless network and for wireless devices that are able to implement these methods to dynamically allocate their radio spectrum access. These methods and devices must be capable of assessing not only the availability of radio spectrum resources, but the quality of those resources. Further, these methods and devices must assess radio spectrum access not only in terms of frequency bands or channels, but non-contiguously in terms of frequency, time, and geographic position. These novel methods and devices must also facilitate the adaptive allocation of radio spectrum access by providing guidance regarding the rationale behind a failed negotiation in an effort to improve future performance.
These novel methods and wireless devices are beneficial to the operation of existing, pre-planned wireless networks, as they provide a dynamic means of modifying radio spectrum access in response to changing radio spectrum conditions.
Further, these novel methods and devices are especially beneficial to configuration and operation ad hoc wireless systems. They provide a means to identify the accessible radio spectrum and to assess the quality of that accessible radio spectrum. Through this assessment, the invention could allocate an “optimum” set of radio spectrum access parameters for a communication session under a given set of ad hoc network conditions.